"We have about eight months of dry season ahead, and our major rivers are at historic lows at the end of the rainy season," said Robyn Felix, spokeswoman for the Southwest Florida Water Management District.

"It is a serious situation," she said, "and we really are asking people to conserve."

How dry is it?

Last week, Swiftmud took the emergency step of letting local officials double their pumping from the Tampa Bypass Canal.

Normally, the city of Tampa relies on the Hillsborough River Reservoir to meet the needs of 656,000 people. But now the reservoir has dropped to a point you would expect to see at the end of the dry season, not the beginning.

This is the fourth time Swiftmud has okayed drawing extra water from the bypass canal to make up the difference. The previous times were during droughts in 2000-01, 2006 and 2007.

The withdrawals began Oct. 17, the day after the emergency order was signed, said Elias J. Franco, distribution division manager for Tampa's water department. They will increase the amount of water pumped from the canal from 18-million or 19-million gallons of water a day to nearly 35-million gallons per day.

After two years of drought, rainfall this year appeared to be returning to normal levels. Then, at the end of the summer, it tapered off. As a result, rainfall through September was about 42.2 inches for the area that includes Hillsborough, Pasco and Pinellas counties. That's about 3 inches below the historic average.

And with a drier-than-normal fall and winter forecast, Swiftmud plans to launch a radio campaign promoting conservation within the next several weeks.

"We really want the public to understand because it's been dry and because we haven't been getting a lot of rain since Tropical Storm Fay in August, people are really increasing their lawn-watering," Felix said. "They really need to follow the one-day-a-week watering restrictions."

Typically, the city of Tampa would simply buy more water from Tampa Bay Water if its reservoir were low.

But Tampa Bay Water, the wholesale water supplier for the entire area, has its own supply problems.

The agency is having to keep an unusually small supply of water in its C.W. Bill Young Regional Reservoir in southeastern Hillsborough County.

The $146-million reservoir is the largest in Florida, covering about 1,100 acres. It opened in June 2005 and is designed to hold 15-billion gallons of water skimmed from the Alafia and Hillsborough rivers and the bypass canal for use by customers in Pinellas, Pasco and Hillsborough counties.

For now, however, it contains only 5.7-billion gallons while the agency investigates cracks found in a soil-cement layer of the reservoir wall. On Monday, the board of Tampa Bay Water voted to sue three companies involved in its construction.

The reservoir problems could lead to tighter watering restrictions, according to regional water officials.

"It is a big deal," Franco said of the need to conserve while turning to emergency sources of water. "When you're in a prolonged drought, as we have been for the last several years, being able to fight this thing on both sides is exactly what we need to be doing."

Richard Danielson can be reached at Danielson@sptimes.com or (813) 269-5311.